Yusmadi was elected as the Member of Parliament for Balik Pulau (P.053), Penang during the Malaysian General Election in 2008. He broke the record by winning the seat for the first time ever since 1999 for PKR with the majority of 708 votes against Norraesah Binti Mohamad (UMNO). During his tenure as a Member of Parliament from 2008-2013, he was appointed by His Majesty the King as a Member of the Parliamentary Committee for Anti-Corruption under the umbrella of the Malaysian Anti-Corruption Commission (MACC). He also became an active spokesperson who championed issues relating to education and international affairs. He was appointed to many inter-parliamentarian committees – his posts include Treasurer for the Inter-Parliamentary Union (IPU Malaysia) and Secretary for the ASEAN Inter-Parliamentary Myanmar Caucus (AIPMC), the Malaysia-European Union Caucus, the Malaysia-South Korea Caucus and the Malaysia-Indonesia Caucus.
On the 27th of August 2018, Yusmadi was appointed as a Senator for the Upper House (Dewan Negara) of the Malaysian Parliament. He will serve as Senator until August 2021.
Senator Yusmadi Yusoff was appointed as the Chairman of the Senate Reform Working Committee. The appointment was made unanimous by all senators in the Dewan Negara on 20 December 2018. The working committee was set up to improve the institution. The establishment of a discussion between the members of the committee and the consent of the Senate President Tan Sri SA Vigneswaran. Among the matters to be proposed for the Senate reform is to raise the independence of the Senate as provided by the Constitution and to educate the public on the function of the institution.
